The incidence of diabetes continues to increase worldwide, leading to an enormous burden on health systems and the cost of health care. A significant fraction of Type 1 and 2 diabetic patients will experience serious microvascular diabetic complications such as peripheral neuropathy (DPN). DPN patients initially experience positive sensory symptoms in the feet such as paresthesias, as well as negative symptoms such as numbness; with progressive loss of lower extremity sensation, motor weakness results leading to loss of balance, falls, ulceration and lower-limb amputations. Currently, glucose control and pain management are the backbones of treatment for diabetic neuropathy. Unfortunately, pain medications offer only symptom management and do not alter the course of the disease. Furthermore, patients with painful neuropathy often need other agents to palliate their symptoms, including antidepressants, anticonvulsants, serotonin-norepinephrine reuptake inhibitors, opiates, and topical medications. Thus, a dire unmet need for interventions able to reduce or slow progression remains. Praetego Inc. plans to advance new chemical entities (NCEs) in the class of Amadorins for the treatment of DPN pathogenesis. Though hyperglycemia is the key common factor linking all diabetic complications, drugs targeting the indirect pathways linked to hyperglycemia have not succeeded in clinical trials. In contrast, two chemically unrelated drugs, aminoguanidine and pyridoxamine, targeting different chemical mechanisms to inhibit the formation of advanced glycation end-products (or AGEs), reached phase 3 clinical trials for another complication, diabetic nephropathy. Our focus in this grant is to advance drug development of new potent Amadorin AGE inhibitors, evolved from pyridoxamine by rational design, that already are showing preclinical efficacy. In this SBIR proposal, we advance the early drug development of PTG-605, the most potent and NCE candidate discovered so far. We focus on validating in vitro efficacy and establishing safety by comparing it to a newly designed analogue PTG-630. We will show that our mechanism- based SAR can successfully design novel and potent Amadorins with therapeutic potential against DPN. These objectives will be accomplished through the following aims: (1) characterize and compare the in vitro post-Amadori inhibitory potency and anti-oxidative properties of the two novel Amadorins, (2) develop mass spectral analytical methods to measure the two compounds in rodent plasma samples, and (3) determine the in vitro and in vivo safety profiles of the two compounds. Our findings will be critical for moving into IND- enabling GLP preclinical safety and efficacy efforts. Comparative safety screening of potential NCEs is crucial for commercial decisions on advancing a preferred candidate through a development program.